pthread（POSIX Threads）本身并不直接支持任務隊列

以下是一個簡單的C語言示例，展示了如何使用pthread和隊列實現一個簡單的線程池：

#include<stdio.h>
#include <stdlib.h>
#include <pthread.h>
#include <stdatomic.h>

#define QUEUE_SIZE 10
#define NUM_THREADS 4

typedef struct Task {
    void (*func)(void *);
    void *arg;
} Task;

typedef struct TaskQueue {
    Task queue[QUEUE_SIZE];
    atomic_int head;
    atomic_int tail;
    pthread_mutex_t lock;
    pthread_cond_t cond;
} TaskQueue;

typedef struct ThreadPool {
    pthread_t threads[NUM_THREADS];
    TaskQueue task_queue;
} ThreadPool;

void task_queue_init(TaskQueue *task_queue) {
    task_queue->head = ATOMIC_VAR_INIT(0);
    task_queue->tail = ATOMIC_VAR_INIT(0);
    pthread_mutex_init(&task_queue->lock, NULL);
    pthread_cond_init(&task_queue->cond, NULL);
}

void task_queue_push(TaskQueue *task_queue, Task task) {
    pthread_mutex_lock(&task_queue->lock);
    while ((task_queue->tail + 1) % QUEUE_SIZE == task_queue->head) {
        pthread_cond_wait(&task_queue->cond, &task_queue->lock);
    }
    task_queue->queue[task_queue->tail] = task;
    task_queue->tail = (task_queue->tail + 1) % QUEUE_SIZE;
    pthread_cond_signal(&task_queue->cond);
    pthread_mutex_unlock(&task_queue->lock);
}

Task task_queue_pop(TaskQueue *task_queue) {
    pthread_mutex_lock(&task_queue->lock);
    while (task_queue->tail == task_queue->head) {
        pthread_cond_wait(&task_queue->cond, &task_queue->lock);
    }
    Task task = task_queue->queue[task_queue->head];
    task_queue->head = (task_queue->head + 1) % QUEUE_SIZE;
    pthread_cond_signal(&task_queue->cond);
    pthread_mutex_unlock(&task_queue->lock);
    return task;
}

void *thread_pool_worker(void *arg) {
    ThreadPool *thread_pool = (ThreadPool *)arg;
    while (1) {
        Task task = task_queue_pop(&thread_pool->task_queue);
        task.func(task.arg);
    }
    return NULL;
}

void thread_pool_init(ThreadPool *thread_pool) {
    task_queue_init(&thread_pool->task_queue);
    for (int i = 0; i < NUM_THREADS; i++) {
        pthread_create(&thread_pool->threads[i], NULL, thread_pool_worker, thread_pool);
    }
}

void thread_pool_add_task(ThreadPool *thread_pool, void (*func)(void *), void *arg) {
    Task task = {.func = func, .arg = arg};
    task_queue_push(&thread_pool->task_queue, task);
}

int main() {
    ThreadPool thread_pool;
    thread_pool_init(&thread_pool);

    // 添加任務到線程池
    for (int i = 0; i < 20; i++) {
        thread_pool_add_task(&thread_pool, my_function, (void *)(intptr_t)i);
    }

    // 等待所有任務完成
    // ...

    return 0;
}

這個示例中，我們創建了一個線程池，其中包含一個任務隊列和四個工作線程。我們可以向線程池添加任務，這些任務將被工作線程從隊列中取出并執行。注意，這個示例僅用于演示目的，實際應用中可能需要考慮更多細節，例如關閉線程池、處理錯誤等。